Growth performance, nutrient utilization, rumen fermentation, blood biochemistry, and carcass traits of lambs fed Atriplex nummularia L. hay-based diet supplemented with yeast or bacterial direct- fed microbial

Direct fed microbial may enhance the utilization of halophyte forages leading to improved animal growth and productivity. This study was conducted to evaluate Atriplex hay-based diet supplemented with yeast (Saccharomyces cerevisiae; SC) or bacteria (Bacillus subtilis and Lactobacillus casei; BAC) on lamb growth performance, digestibility, rumen fermentation, and carcass characteristics. Fifteen Barki lambs (90 ± 7 days of age and 18.6 ± 0.41 kg SE body weight; BW) were randomly assigned to three treatments for 120 days as follows: Control (basal diet without supplementation), SC and BAC diets, the basal diet supplemented with SC or BAC at 2 g/head/day, respectively. All lambs had similar dry matter (DM) intake, while lambs fed SC or BAC dies had higher (P < 0.05) total gain and average daily gain than those fed the control diet. Supplementation of SC or BC increased (P < 0.05) the digestibility of DM, organic matter, and acid detergent fiber, tended to decrease (P < 0.05) the urine N excretion and enhanced the N balance compared to the control. Ruminal pH, acetate, total volatile fatty acids concentrations, and bacterial protein were increased (P < 0.05), while creatinine and urea concentrations were decreased (P < 0.05) by both additives. Compared to other diets, the BAC diet reduced (P < 0.05) triglycerides, total lipids, kidney fat, and eye muscle fat. In conclusion, both additives resulted in similar positive growth performance and feed utilization, while only the BAC additive had a beneficial advantage in reducing the fat content of the carcass.